The plan, which would be activated without President Asif Ali Zardari’s consent, provoked an angry reaction from Pakistan officials last night. Barack Obama would order troops to parachute in to protect key nuclear missile sites. These include the air force’s central Sargodha HQ, home base for nuclear-capable F-16 combat aircraft and at least 80 ballistic missiles.

A US source told the Sunday Express: “The plan is green lit and the president has already shown he is wiling to deploy troops in Pakistan if he feels it is important for national security.” However, news of the plan has further increased tension between the US and Pakistan with relations already at an all-time low after the Operation Geronimo raid by the US Navy Seal special forces team that killed bin Laden at the house where he had been hiding in Abbottabad, near to a Pakistan military academy.

An angry Pakistani official said: “Pakistan has an elaborate command and control structure and is fully capable of defending its strategic assets under any circumstances and does not need any assistance from any country, including the US, to safeguard its nuclear installations.”

The plan reflects growing concern over reprisals for the al-Qaeda terror leader’s death. More than 80 people were killed and 140 injured when two Taliban suicide bombers struck at a military academy in the north-western town of Charsadda on Friday.

Alex Neill, of the Royal United Services Institute, said: “The United States places its own national security issues above all other sovereignty issues and trust in Pakistan’s abilities are extremely low.”

“If Obama can persuade congress that placing US troops at the installations is necessary to protect US citizens from possible nuclear attack, then that’s what he will do.” The Pentagon on Saturday refused to deny the existence of the plan, with a spokesman saying only: “We are confident that Pakistan has taken appropriate steps towards securing its nuclear arsenal.”